|
|
A181758
|
|
Greatest prime closest to n^3.
|
|
1
|
|
|
2, 7, 29, 67, 127, 211, 347, 509, 727, 997, 1327, 1733, 2203, 2741, 3373, 4099, 4909, 5827, 6857, 7993, 9257, 10651, 12163, 13829, 15629, 17579, 19681, 21961, 24391, 26993, 29789, 32771, 35933, 39301, 42863, 46663, 50651, 54869, 59333, 63997, 68917, 74093, 79493, 85193, 91127, 97327, 103813, 110597, 117643, 125003
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
EXAMPLE
|
29 is the greatest prime closest to 3^3 = 27.
|
|
MATHEMATICA
|
f3[n_]:=Module[{n3=n^3, np1, np2}, np1=NextPrime[n3, -1]; np2=NextPrime[n3]; If[(n3-np1)<(np2-n3), np1, np2]];
Table[f3[i], {i, 50}]
|
|
PROG
|
(PARI) a(n) = {if(n == 1, return(1)); my(n3 = n^3, gp = nextprime(n^3), lp = precprime(n^3)); if(n3 - lp < gp - n3, return(lp) , return(gp) ) } \\ David A. Corneth, May 25 2021
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|